OpenSearch - Instance type migration stop in "Step 3 of 4: Copying shards to new nodes"

Hello Patrick, I recommend to open a support case to resolve the issue. Do you have any support plan for you account where the OpenSearch cluster runs? When opening a support case, make sure to open it from the same account as your OpenSearch cluster. Also, share the OpenSearch domain ARN and the issue description in the support case correspondence.

Note: If your cluster is stuck in the "Processing" state for more than 24 hours, then your cluster needs manual intervention. Also, if you haven't made any configuration changes but the node count is higher than expected, then a software patch might be in progress.

• https://aws.amazon.com/premiumsupport/knowledge-center/opensearch-domain-stuck-processing/?nc1=h_ls